1. Field of the Invention
The present invention relates generally to a character developing apparatus for developing an outline character in a character string on a bitmap memory and, more particularly, to a character developing apparatus including an outline character forming circuit constructed of a plurality of pipeline-connected processing circuits.
2. Description of the Related Art
An outline character forming method has been utilized, wherein a character pattern is formed from data (outline data) indicating a character outline in order to form the character pattern of kanji (Chinese character), etc. According to such an outline character forming method, there are proposed pipeline processing circuits for the purpose of reducing an outline character creation processing time, wherein outline character creation processing is divided into a plurality of processes, and the independent processing circuit each takes charge of the divided process.
In the outline character creation (forming) circuit employing such pipeline processing circuits, a technology of sufficiently exhibiting a function of the pipeline is desired.
FIGS. 21 and 22 are explanatory diagrams showing the prior art.
As illustrated in FIG. 21, a character developing apparatus includes a control CPU (central processing unit) 90, an outline character forming circuit 91, a character storage memory 92, a character transfer circuit 93, a bitmap memory 94 and a control memory 95.
The control CPU 90, on receiving a to-be-developed character string containing the outline characters, processes character codes of the character string in sequence. This character storage memory 92 stores the developed character patterns (the character pattern developed from outline data and the character patterns originally developed as character patterns) and also outline data of the characters.
Supposing that the characters of the character string are defined as characters (non-outline characters) developed in the form of the character patterns, the character transfer circuit 93 transfers the relevant character pattern to the bitmap memory 94 from the character storage memory 92. On the other hand, if the characters of the character string are defined as outline characters that are not developed into the character patterns, the outline character forming circuit 91 is started up. The outline character forming circuit 91 creates the character patterns by use of the outline data in the character storage memory 92. Then, the character transfer circuit 93 transfers the thus formed character patterns to the bitmap memory 94.
An explanation will be given referring to FIG. 22. First through fourth characters [A]-[D] in the character string are defined as non-outline characters. With respect to these characters, the character storage memory 92 stores the character patterns, and therefore the character patterns are transferred from the character storage memory 92. On the other hand, a fifth character [E] is an outline character. The character storage memory 92 stores no character pattern with respect to the outline character. For this reason, a character pattern is, after being created by the outline character forming circuit 91, transferred to the bitmap memory 94.
As illustrated in FIG. 22, forming this outline character involves initial processing, a change of a character size, a correction of a line width, rendering an outline and filling within the outline. For performing these processes within a short period of time, the outline character forming circuit 91 makes use of pipeline processing circuits, wherein each processing is conducted by a dedicated processing circuit.
Based on the prior art, however, the character strings are processed in sequence, and, hence, there exists a necessity for waiting a time for forming the outline character. For this reason, if the characters (non-outline characters) with the already-formed character patterns and the outline characters are so arranged as to be mixed in the character string, this conduces to a problem in which the character can not be developed at a high speed.